1. Field of the Invention
The present invention relates to apparatus for removing the milking cluster or claw of an automatic milking system from an animal such as a cow when the flow of milk therefrom diminishes to a predetermined level. More particularly, the invention relates to apparatus for maintaining the milking claw in a retracted position when the milking machine is uncoupled from all power and vacuum supplies.
2. Description of the Related Art
Automatic milking machines are widely used in a variety of types of dairies such as in stanchion and tie-stall dairies. Many of these milking machines include apparatus for automatically removing the milking cluster or claw from the udder of the cow being milked when the milk flow level has diminished to a predetermined level. The milking claw is then attached to an adjacent cow to be milked, and the process is repeated until all the cows within the service area of the milking machine have been milked. Thereafter, a new group of animals is brought to the milking machine or, in the case of portable machines, the milking machine is transported to another animal or group of animals to be milked. This invention pertains particularly to portable milking machines, although it can be used with more permanently fixedly mounted machines as well.
The automatic milking claw removal devices of milking machines generally use a vacuum powered cylinder for removing the claw from the cow's udder and retracting the claw to a predetermined position away from the cow. An example of such a removal device is disclosed in U.S. Pat. No. 3,690,300, the disclosure of which is hereby expressly incorporated by reference. U.S. Pat. No. 3,690,300 discloses an apparatus for removing the teat cups of a milking claw in response to the detection of milk flow at a predetermined level. Milk flow is detected by a flow indicator positioned in the milk flow line between the milking claw and the milk collection reservoir. When the milk flow diminishes to the prescribed threshold value, the flow indicator emits a signal which actuates means for reducing the vacuum pressure at the milking claw and supplying atmospheric air into the claw, prior to removal of the teat cup cluster thereof. The milking claw is then retracted through activation of the vacuum cylinder. The cylinder, which is generally vertically oriented, includes therein a reciprocably-mounted piston movable in response to a change in pressure in the space between the cylinder and top of the piston. The milking claw is coupled to the piston through a cord which extends from the piston and outwardly from the cylinder. The cylinder space above the piston is connected through an inlet to the vacuum line used to effect milking of the cow. Upon completion of the milking, as indicated by the reduction in milk flow to the predetermined level, the piston is drawn upwardly by the vacuum to withdraw the cord into the cylinder and lift the milking claw from the cow. Other examples of milking claw removal apparatus are disclosed in U.S. Pat. Nos. 4,523,545 and Re. 29,848.
A problem arises, however, when the milking machine is to be transported from one location to another within the dairy or is otherwise shut off or disconnected from its electrical and vacuum supply lines. When either of these events occurs, the piston and attached milking claw are drawn by the force of gravity to the floor, absent coupling of the claw with a suitable retention device. When the milking claw drops to the floor, it becomes needlessly contaminated, thereby causing delay in the milking process until the milking claw is properly cleansed. Attempts to correct this problem have included provision of a hook or similar retaining member to the cylinder upon which the milking claw can be suspended or, in the case with portable machines, the operator's carrying of the milking machine in one hand and the milking claw in the other hand. Neither of these corrective measures is acceptable because they do not adequately prevent the possibility of contamination. In addition, these measures necessitate additional time or handling on the part of the operator.
Accordingly, it is an object of the present invention to provide a milking claw retraction and retention device which overcomes the aforedescribed disadvantages and reliably secures the milking claw in a retracted position away from the ground.
Another object of the present invention is to provide a milking claw retraction and retention device which is simple to operate and minimizes the need for operator supervision.
Another object of the present invention is to provide a milking claw retraction and retention device which operates automatically to retract the milking claw from a cow and retain the claw in a retracted position upon determination of a milk flow at a predetermined level.
Yet another object of the present invention is to provide a milking claw retraction and retention device which maintains the milking claw in a retracted position following withdrawal of the claw from the animal, even when the supply of electricity and negative pressure to the machine is shut off.
Still another object of the present invention is to provide a milking claw retraction and retention device which is simple in design and inexpensive to manufacture.